| From foo@baz Sun May 27 17:33:38 CEST 2018 |
| From: Joerg Roedel <joro@8bytes.org> |
| Date: Wed, 11 Apr 2018 17:24:38 +0200 |
| Subject: x86/pgtable: Don't set huge PUD/PMD on non-leaf entries |
| |
| From: Joerg Roedel <joro@8bytes.org> |
| |
| [ Upstream commit e3e288121408c3abeed5af60b87b95c847143845 ] |
| |
| The pmd_set_huge() and pud_set_huge() functions are used from |
| the generic ioremap() code to establish large mappings where this |
| is possible. |
| |
| But the generic ioremap() code does not check whether the |
| PMD/PUD entries are already populated with a non-leaf entry, |
| so that any page-table pages these entries point to will be |
| lost. |
| |
| Further, on x86-32 with SHARED_KERNEL_PMD=0, this causes a |
| BUG_ON() in vmalloc_sync_one() when PMD entries are synced |
| from swapper_pg_dir to the current page-table. This happens |
| because the PMD entry from swapper_pg_dir was promoted to a |
| huge-page entry while the current PGD still contains the |
| non-leaf entry. Because both entries are present and point |
| to a different page, the BUG_ON() triggers. |
| |
| This was actually triggered with pti-x32 enabled in a KVM |
| virtual machine by the graphics driver. |
| |
| A real and better fix for that would be to improve the |
| page-table handling in the generic ioremap() code. But that is |
| out-of-scope for this patch-set and left for later work. |
| |
| Reported-by: David H. Gutteridge <dhgutteridge@sympatico.ca> |
| Signed-off-by: Joerg Roedel <jroedel@suse.de> |
| Reviewed-by: Thomas Gleixner <tglx@linutronix.de> |
| Cc: Andrea Arcangeli <aarcange@redhat.com> |
| Cc: Andy Lutomirski <luto@kernel.org> |
| Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: Brian Gerst <brgerst@gmail.com> |
| Cc: Dave Hansen <dave.hansen@intel.com> |
| Cc: David Laight <David.Laight@aculab.com> |
| Cc: Denys Vlasenko <dvlasenk@redhat.com> |
| Cc: Eduardo Valentin <eduval@amazon.com> |
| Cc: Greg KH <gregkh@linuxfoundation.org> |
| Cc: Jiri Kosina <jkosina@suse.cz> |
| Cc: Josh Poimboeuf <jpoimboe@redhat.com> |
| Cc: Juergen Gross <jgross@suse.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Pavel Machek <pavel@ucw.cz> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Waiman Long <llong@redhat.com> |
| Cc: Will Deacon <will.deacon@arm.com> |
| Cc: aliguori@amazon.com |
| Cc: daniel.gruss@iaik.tugraz.at |
| Cc: hughd@google.com |
| Cc: keescook@google.com |
| Cc: linux-mm@kvack.org |
| Link: http://lkml.kernel.org/r/20180411152437.GC15462@8bytes.org |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/mm/pgtable.c | 9 +++++++++ |
| 1 file changed, 9 insertions(+) |
| |
| --- a/arch/x86/mm/pgtable.c |
| +++ b/arch/x86/mm/pgtable.c |
| @@ -1,5 +1,6 @@ |
| #include <linux/mm.h> |
| #include <linux/gfp.h> |
| +#include <linux/hugetlb.h> |
| #include <asm/pgalloc.h> |
| #include <asm/pgtable.h> |
| #include <asm/tlb.h> |
| @@ -577,6 +578,10 @@ int pud_set_huge(pud_t *pud, phys_addr_t |
| (mtrr != MTRR_TYPE_WRBACK)) |
| return 0; |
| |
| + /* Bail out if we are we on a populated non-leaf entry: */ |
| + if (pud_present(*pud) && !pud_huge(*pud)) |
| + return 0; |
| + |
| prot = pgprot_4k_2_large(prot); |
| |
| set_pte((pte_t *)pud, pfn_pte( |
| @@ -605,6 +610,10 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t |
| return 0; |
| } |
| |
| + /* Bail out if we are we on a populated non-leaf entry: */ |
| + if (pmd_present(*pmd) && !pmd_huge(*pmd)) |
| + return 0; |
| + |
| prot = pgprot_4k_2_large(prot); |
| |
| set_pte((pte_t *)pmd, pfn_pte( |